A woman has died after being hit by debris falling from a building in Mayfair, central London.

The woman, believed to be in her 20s, was pronounced dead at the scene after building work fell on her in Hanover Square, the London ambulance service (LAS) said.

An air ambulance was sent and extensive efforts were made to resuscitate the woman to no avail.

An LAS spokeswoman said on Thursday: "We were called at 11.30am today to reports of building work fallen on a person at Hanover Square.

"We sent two cycle responders, two ambulance crews, London's air ambulance, members of the hazardous area response team and an officer to the scene.

"Extensive efforts were made to resuscitate a woman, reported to be in her 20s, but sadly she was pronounced dead at the scene by the air ambulance doctor."

Police also attended the scene. A Scotland Yard spokeswoman said: "At this stage it is believed an unknown object hit the woman." A Health and Safety Executive spokeswoman said they were aware of the incident and were "making initial inquiries". Three workers on a cigarette break outside Vogue House, which also overlooks 5 Hanover Square, said barricades were in place around the building but were removed a few months ago.

One woman said: "We walk past there every day. It's quite scary – that it could have been any of us."